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Thread: Template routing for a newbie

  1. #1

    Template routing for a newbie

    Hi all,

    I'm about to undertake my first template project with my 1/2" router and want to make sure I get it right - so I've come to all you old pros with a few questions

    My project: I have had a couple of mirrors cut at the factory with fairly large corner radiuses (2-1/2"). I've attached an example photo of the inspiration that I'm using below. My plan is to adhere these mirrors to a 3/4" piece of Baltic birch plywood that will be used as a door for a medicine cabinet. The 13-ply edges will be finished with Osmo Polyx and left exposed for a modern look. I'd like to use the mirrors as templates and use a router to make an exact copy of the mirrors' dimensions/shapes in the plywood. In other words, I'd like the plywood cabinet door to be a flush copy of the mirror.

    I do not have a router table yet so this would be done with a 1/2" handheld router.

    I do not want to adhere the mirrors to the plywood panels until *after* I have routed them to the mirrors' dimensions. This is in case I make an error and wreck the plywood panel somehow during the process and want to start over, and also so that I can more easily sand the edges and apply the Osmo polyx and not get it on the mirror's edge.

    My questions:

    1. How do you decide if your template (mirrors in my case) go on top of the workpiece or underneath the workpiece?

    2. If I place the templates (mirrors) on top of the workpiece, do you think there is very much risk of shattering the mirrors from the vibration of the router? I suppose the same risk may apply even if I place the mirrors underneath the workpiece.

    3. Regardless of whether the mirrors/templates are placed underneath or on top of the workpiece, I plan on applying painter's tape to the edges of the mirrors to avoid them being scratched by the router bit's bearing. Is this a sound idea or is there a reason I would not want the bearing riding on top of tape?

    4. What kind of router bit would best achieve a finely finished edge on the Baltic birch panels (since it will be left exposed)? From the reading I've done it sounds like I want a downcut spiral bit, but there is such a wide variety of template bits so I am not sure on exactly which bit would best serve my purpose. I normally buy Whiteside bits.

    5. I know it will be an easier job with the router if I cut the panels close to the final dimensions, but how close is this normally done?

    Thanks for reading!
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  2. #2
    Join Date
    Mar 2019
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    Quote Originally Posted by Ken Cobbing View Post
    1. How do you decide if your template (mirrors in my case) go on top of the workpiece or underneath the workpiece?
    Either way, the location of the bearing (top or bottom) will dictate where you put the template. The template follows the bearing. I like the bearing on top in a router table situation, closest to the operator, but if you order such a router bit, it is backwards, so I am referring to a bearing on the bottom bit. This is because the bit is inverted in a router table. However, more often than not the bearing is on the bottom and clamp the workpiece to the template, which I think is safer.

    I think if I were you, I would invest in a router table, as template routing is safer on a table. Tables are cheap, a couple hundred bucks on craigslist. 3/4 is a lot of stock to remove in a single pass, and you are at the mercy of your rough scribe line on the plywood. You would have to get really, really close to be safe, like a 1/16th or less. With a table, you can sneak up on your line

    Quote Originally Posted by Ken Cobbing View Post
    2. If I place the templates (mirrors) on top of the workpiece, do you think there is very much risk of shattering the mirrors from the vibration of the router? I suppose the same risk may apply even if I place the mirrors underneath the workpiece.
    I would make a template out of posterboard, then transfer that to 1/4" mdf, then work the mdf with sanding and files and rasps to get within a 1/16 of the mirror. So far, the mirror has stayed away, far away, from any power tool. Then, use the 1/4" mdf to mill your substrate, which is your 3/4" ply. Then attach the mirror. If you want to be really safe and precise, use the 1/4" template to make a 3/4" template to which you can clamp the work piece to. Otherwise, many folks just use double stick tape.

    Quote Originally Posted by Ken Cobbing View Post
    3. Regardless of whether the mirrors/templates are placed underneath or on top of the workpiece, I plan on applying painter's tape to the edges of the mirrors to avoid them being scratched by the router bit's bearing. Is this a sound idea or is there a reason I would not want the bearing riding on top of tape?
    See above. The mirrors stay far away from any router. I would put them inside the house. They are only used to trace onto the poster board, and once you have a 1/4" mdf template to compare to.


    Quote Originally Posted by Ken Cobbing View Post
    4. What kind of router bit would best achieve a finely finished edge on the Baltic birch panels (since it will be left exposed)? From the reading I've done it sounds like I want a downcut spiral bit, but there is such a wide variety of template bits so I am not sure on exactly which bit would best serve my purpose. I normally buy Whiteside bits.
    Go to your supplier, like Rockler or Woodcraft and get a router bit that has a steep angle to the cutting edges, called a downcut spriral. Whether you get a downcut spiral, or its cousin, the upcut spiral will depend on whether you take my advice and get a router table. With a router table, you would use a upcut spiral which would force the work piece up to the template (actually down, because you're using a router table and the template is on the bottom)

    Quote Originally Posted by Ken Cobbing View Post
    5. I know it will be an easier job with the router if I cut the panels close to the final dimensions, but how close is this normally done?
    The 1/4" template should be dead on. If you take your time your finished panel will be dead on.

    I attach a picture of what I make if I am using a 3/4" clamping template and a 1/4" double stick template. I would recommend making some silly shapes and practicing using the template and router before tackling the 3/4" final mounting piece. Its great to practice and get the feel of it, and understand which direction you rout to, so as to avoid the dreaded climb cut. The directions are opposite for a hand held router and a router table, as you would expect. I would consult Fine Woodworking and look for an article by Doug Peterman May June 2004. If you're not a member, you may have to pay for the article, but it is a good read for exactly what you are doing. Pat Warner, one of the great long past router Gods, had a few books on the subject and you might be able to find one of his books on eBay, but for something quite and dirty, Doug Peterman's article is just what the doctor ordered.

    Others here are way smarter than I am on this subject and will chime in. Although I am an experienced woodworker, I am a piker compared to many here on this site.
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    Regards,

    Tom

  3. #3
    Join Date
    Jan 2007
    Location
    Ottawa, ON Canada
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    1,468
    Tom has this right. This is seven years bad luck just waiting to happen. Do not use the mirror has a template for your router. Follow Tom's advice to make a template from material that you can cut and sand to match your mirror, and use that for the template.

    Failing all that, find someone local with a CNC router and pay them to mill your plywood. They will be able to do it from a trace of your mirror.
    Grant
    Ottawa ON

  4. #4
    Join Date
    Jan 2010
    Location
    Tampa Bay, FL
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    3,895
    SWMBO is way too superstitious to ever allow working near a mirror.

    Tom's advice is right on. Trace a template, put the mirror in the house, then rout away. I also agree a router table is a far safer way of doing this, though it can be done with a handheld router.
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

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